280 ZX Running fault

[silvos]

HELP. I have a 1982 US Spec 2 str car. It is nearly there and ready to MOT register etc. It has a running fault. It will start first time every time, tick over lovely, but it will not rev cleanly. If you "feather" the throttle the revs will build up but not well. Any thoughts Cheers Silvos

 

[peter_s]

I would take a look at the MAF as a start. Clean it and see if there is any difference.

It might be fuel related since you say it works well at idle. It might not get enough fuel to support higher revs. Check the fuel pressure.

 

[Huw]

Silvos

Couple of things can cause the engine to stumble on acceleration.

• Incorrect ignition timing - too retarded, or possibly distributor governor not working or stuck
• The flap on the air flow meter sticking. Check the flap moves freely. Do not be tempted to shove anything down into the housing to clean it as there is a really delicates thermocouple in the housing.
• Fuel pressure as mentioned, do a pressure test
• Biggest culprit is air leaks at these points- PVC valve ; dipstick or oil filler cap; intake manifold gasket ; airflow meter hoses this can crack along the joints and be difficult to spot.
• Possible EFI circuit fault. You would need to check each component in turn. I’d start with cold start valve and injectors.

Hope this helps, keep us posted.

Huw

 

[niroshann]

Relating to fuel pressure, take a look into the fuel tank via the hatch in the boot area. Might be a lot of rust/debris that might be causing enough of a clog to just keep it running at lower revs.